Funds are requested for partial support of the fourth Conference on Folic Acid, Vitamin B 12 and One Carbon Metabolism, to be held under the auspices of the Federation of American Societies for Experimental Biology (FASEB) from August 2-7, 1992 at Vermont Academy, Saxton's River, Vermont. This conference offers a unique opportunity for physician scientists and basic scientists from a broad group of disciplines, who share an interest in folate, B12 and one carbon metabolism, to interact both formally and informally. The last two conferences have been fully subscribed, and participation at this conference will be limited to 150 people. Funds are requested to permit broad participation from international scientists and to allow graduate students, residents and postdoctoral fellows working in this area to attend the meeting. A detailed program is presented, and includes both well established scientists and scientists just entering the field. A major focus of the meeting will be the development and testing of chemotherapeutic agents directed against folate-dependent enzymes and enzymes involved in folate and cobalamin biosynthesis. Sessions have been scheduled on the mechanisms of folate- and cobalamin-dependent enzymes, on the structures of these enzymes, on the transport and compartmentation of folates, antifolates and cobalamin derivatives, and on clinical evaluation of antifolates now in various phases of clinical trial. A second major focus will be on the role of folate and B12-dependent enzymes in metabolism. Sessions are planned on the evaluation of the nutritional status of both normal and diseased humans, and the effects on metabolism of drugs that intervene in folate and cobalamin-dependent reactions. The program will be complemented with poster sessions. The poster sessions offer many opportunities for informal discussion and allow students, residents and postdoctoral fellows, as well as established scientists, an opportunity to present and discuss their work. 'Re most interesting new research presented at the conference will be disseminated to a much wider audience in the form of one or more "state-of-the-art" reviews in the FASEB Journal.